Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The experiments described in this paper serve as a contribution to the solution of the discrepancies which exist in the assay of ATP:thiamine diphosphate phosphotransferase activity (EC 2.7.4.15), presently in use as a tool for the diagnosis of Leigh's disease (SNE, subacute necrotizing encephalomyelopathy). The results obtained with this phosphotransferase assay can, in part, be explained by the presence of thiamine triphosphate (ThTP) in the preparation of thiamine diphosphate (ThDP) used as a substrate, by the inhibition by ATP of the ThTP phosphohydrolase activity, present in fractions of rat brain homogenates, and by the stimulation by ThDP of the ATPase activity. When [2(-14)C-thiazole]thiamine was used for the synthesis of [14C]ThTP in fractions of rat brain, it was found that after chromatographic separation of thiamine and its phosphates, 14C radioactivity could be demonstrated in the ThTP fractions, even in the absence of an enzyme source. Probably a complex is formed between [14C]thiamine and a phosphate ester which behaves chromatographically as ThTP. It is concluded that the assay system for the measurement of ThTP synthesis in its present form is, in our hands, not suitable for diagnostic purposes.
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PMID:Studies on ATP: thiamine diphosphate phosphotransferase activity in rat brain. 21 45

A membrane-bound nonspecific triphosphatase of E. coli was solubilized and purified to a homogeneous SDS-acrylamide gel electrophoresis band. It was found to be a single polypeptide of 16 kDa requiring no Mg2+, with an optimal pH at 6.5. The substrate specificity was broad and a nonspecific Mg2+-independent ribonucleoside-triphosphatase (NTPase) activity was expressed together with thiamin-triphosphatase activity. The molecular size and characteristics were clearly different from the known NTPase (EC 3.6.1.15). Using the purified thiamin-triphosphatase II, ATP:thiamin-diphosphate phosphoryl transferase (EC 2.7.4.15) activity was demonstrated with an optimal pH of approx. 5.3. Considering its kinetic parameters and other characteristics, however, the thiamin triphosphate synthesizing activity was not thought to take part in cellular thiamin triphosphate synthesis. The possibility that thiamin-triphosphatase II plays a part in the hydrolysis of thiamin triphosphate to control its cellular level is suggested.
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PMID:Nucleoside-triphosphatase and hydrolysis of thiamin triphosphate in Escherichia coli. 302 93